Process for preparing certain acylcholine esters and their salts



Patented Aug. 27, 1935 "f foifthe'product on ot salts of"- aliphatic acid es- Q N ESTEBS of .Newi'Jersey.

. omawin orignalapl ibation March-3011931, I Y -Serial No.'526,549. Divided and thisapplication- -"I-'hi's isa division army application "Serial No.

- paring certa'in acyl -ch'ol'ine =esters, etc., issued on atentfNo. 1 3957343; I relates to improved, processes ri ge'rieral' such P13 t h *e'sterification' (or acylation) 1 salts with aliphatic; acida'nonp1me "and itsfesters,fand inor especially -acetyl 'cholineiand"its "salts, have-"achieved considerable' pharmacological jimportance f in *recent (years, but l'IISpl lle'bf f'thQ large amount of" work 5: i appea to thie'jSalts of. acetyl? Choline; since "thefl'gener ndication re that jthey would be fl 'ikelyltofbe"tIie'mOSta'ct which ha been done with; choline compounds, they. hav not .foundf the" extensive "application 'fi'hu ii ni erap w ich, h b expected irq rthe therape i m cq'le i e i'c' ossib'ilitiesindicated'bytliel harudi'esK'Thisisdue tothefa'ctthat he'se preparations vhave not been in 'a form and interestingijconipounds oi the series :Tlie production 'ef yl choline,

. i utjitapp'ears 'that not'ur itiLquite recently have they been generally isolated'inithe form of pure and definitely" identified entities.

..I.amfarniliar;with the work of Baeyer (Ann. 142,

325"(1867) )f Nothnagel (Arch. Pharm. 232, 265 (1894) Fourneau and Page (Bull. Soc. Chim. [4]

15, 552 (1914) Abderhalden and Paffrath (Fermentforschung 8, 299 (1925) C. A. 19, 2532 (1925)), and Hunt (Pharmacol. '7, 306 (1915)), as well as the more recent investigations of Jones and Major (Jr. Amer. Chem. Soc. 52,307 (1930)) in this field. So far as I have been able to learn by a study of the literature, the latter were the first to succeed in isolating the pure acetyl-choline chloride and iodide and to study and'describe their physical and chemical properties. I am also familiar with new processes developed by Jones and Major for making their salts.

At the suggestion of Randolph T. Major, I under'took the task of developing further improved processes for the production of such aliphatic esters of choline and salts, and have now succeeded in working out proceses which are relatively technically simple, render good yields, and produce preparations of a satisfactory degree of purity.

' "withchloro' ethylacetatefwhile i d tion s h 1d make I'(dummy-and"adaptable o such e forms or; therapeutic ANDTHEIRSALTS N. Jr, a corporation;

'I'heold methods'usedfoi fprodu n eam hoinc -compounds} followed tionsi which either didno -re dlly' le'n fto satis'iactory isolatio I efilciency as to yield and simplicity.

*jBaeyer (supra); in- 1867 "and Nothna'g elks. fa) in l89 4, car ried onltheir experiments f 'J e f a XSu a) 92. ,re fq ior a t l 11611119 br fi bn-.. ,u I choline iillfthe presence ofianf'enzy of theseinvestigatorsi 'su'c'ceededj L compound or Q m; determiningf'itsj and "chemical properties." 1' and thereafter, "studied ,fg'pharm iplliysiol(l gical; action fof.'sol utionsjc. ta 'jlin'e" n'd its'compounds'nnd'rep rt'ed' succeeded irf forming acty such solutions. .Italso. does .n thatihe at any time succee ed .lidefining the, pur su stances.

closed. 7

While it appears, from what has been said, that a number of chemists acylated choline and its simple salts, none of them seems to have succeeded in isolating pure esters of such salts of choline from the products of their reactions, even though it appears that several investigators did succeed in isolating and defining some of the double salts, e. g., chloro platinites and aurichlorides, which, however, are presumably not of especial medicinal interest in the-present stat'eof our knowledge; Thus Baeyer (supra) and later Nothnagel (supra) were unable to isolate pure acetyl choline chloride from the product that they obtained by the action of acetyl chloride on choline chloride. Hunt (supra) did not isolate pure acetyl choline from the product of the interaction of choline and acetyl chloride, nor did Ab- ,derhalden and Paffrath obtain pure acetyl choline by the action of sodium acetate on choline in the presence of an enzyme. Contrary to the general assumption, I have now found that I can obtain pure acyl-choline salts by the action of acyl anhydrides on choline salts, according to the equation:

Byway of illustration I set forth in the following example the preferred forms of the process, which can also readily be followed in the production of other analogous esters and salts,,by ap- I propriate adaptation. 1

Example I .-Accty1 choline chZ0ride.-One part of choline chloride is treated with five parts of acetic anhydride. The mixture is heated at 100 C. in a closed vessel for about one hour in excess of the time required for complete solution. The vessel is then cooled, and the formed acetylcholine chloride is precipitated by means of the addition of anhydrous ether. The precipitate is .filtered off and dried. Thereafter theprecipitatl required for complete solution. The vessel is then cooled andtheformed-propionyl choline chloride is precipitated by, means of the addition of an-' hydrous ether. dried. Thereafter the precipitated mass is puri- Theprecipitate is filtered and fled by dissolving it in, absolute alcohol filtering if necessary and reprecipitating with dry ether.

The formed mass is then filtered off and washed with anhydrous ether. The final product appears as crystals, soluble in alcohol, insolublein ether,

meltingat 1105c. p 7

Example IlL Butyryl-choline chloride.'0ne

part of choline chloride istreated with four parts butyric anhydride. The mixture is heated at 100 C. in aclosed vessel for about one hour in excess of the time required for complete solution of about five hours.

.formedbutyryl choline chloride is precipitated by The vessel is then cooled and the means of the addition of anhydrous ether. The

precipitate is filtered or: and dried. Thereafter v the precipitated mass is purified' by dissolving it in absolute alcohol, filtering if necessary and reprecipitating with dry ether. The final product 1s obtained in the form of crystals.

Example IV.--Acetyl-choline acetate-One part of choline acetate is treated with five parts of acetic anhydride. The mixture is heated at 100 C. in a closed vessel for about one hour in excess of the time required for complete solution,

' or a total ofabout two hours. The vessel is then cooled and the formed acetyl choline acetate is precipitated by means of the addition of anhydrous ether. The precipitate is filtered off and dried. Thereafter the precipitated mass is purified by dissolving in absolute alcohol filtering if necessary and reprecipitating with dry ether. The formed mass'is then filteredofi and washed with anhydrous ether. The final product is obtained in the form of crystals melting at 146- 148 C. v

As will be readily understood, the process may be varied somewhat within reasonable limits as to the actual relative quantities of the materials employed, temperature, etc., without departing from the spirit and scope of the invention disclosed.

It-will thus be seen that by this process it is possible to produce a wide range of acyl-choline salts by simply treating the appropriate salts with a given aliphatic acid anhydride, in the manner described. Thus a variety of salts of choline esters suitable for medicinal use which have not hitherto been produced, and which will considerably extend the armamentarium of the physician with respect to a class of remedial agents which are now assuming an important role in therapy.

salts by dissolving thecorresponding choline salt in an excess of butyric anhydride with the aid of heat, continuing the application of heat until acylation of the choline salt is substantially completed, then cooling and precipitating the formed butyryl choline salt with anhydrous ether, and

purifying the same by re-dissolving in absolute alcohol and reprecipitating with anhydrous ether,

filtering off the reprecipitated crystals and washing with anhydrous ether.

2. The process of preparing salts of butyrylcholine embracing the steps of reacting upon the" corresponding salt of choline with butyric anhydride, precipitating and purifying. the reaction product in substantially the same manner as de- JOSEPH K. CLINE. 

